Synchrotron-based imaging techniques of a 50 million-year-old lizard skin have identified the presence of teeth which are invisible to visible light, demonstrating for the first time that this fossil animal was more than just a skin moult.

Researchers used Synchrotron Rapid Screening X-ray Fluorescence at the Stanford Synchrotron Radiation Lightsource in California to map the chemical make up of a rare fossil lizard skin - powerful x-rays enabled the team to map the presence of phosphorus from teeth in this ancient reptile.

The relative position of the phosphorous in the skin fossil helped the scientists identify the type of lizard. They believe that the more elongated snout in conjunction with the general jaw shape bears a strong resemblance to a shinisaurid lizard (Bahndwivici ammoskius). The presence of phosphorous also demonstrates for the first time that the fossil skin is more than just a moult, as no lizards can shed their teeth along with their skin!

Dr. Phil Manning from the Palaeontology Research group at the University of Manchester said, "Finding the presence of teeth changes almost everything we thought we knew about this fossil. We can identify the type of lizard for the first time, based upon the geometry of the teeth. Our findings also raise some fascinating questions about what happened to the animal after its death. What wiped out its bones but preserved the skin and the ghost of its teeth?

"The technique permits us to tease-out chemical information from fossils, information that you simply cannot see with the naked eye. Such chemical maps can help us see 'ghosts' of original biological structures that only remain in very dilute concentrations in the fossil."

Dr Nick Edwards, a senior author on the paper, said: "This technology changes how we view taphonomy (the study of decaying organisms and how they are fossilized). We can now start looking for traces of animals that are totally invisible in visible light through analysing the bright chemical signature that appear under the powerful gaze of the synchrotron. This 'x-ray vision' will enable palaeontologists to add important information to the biology, anatomy and preservation of ancient life."

The team worked with Dr. Roy Wogelius (also a senior author), who was instrumental in the development of the techniques deployed by the Palaeontology Research Group. Wogelius said: "These techniques are beginning to redefine the way we study Life on Earth. It is simply fascinating to work with biologists, physicists, chemists and palaeobiologists because at the crossroads of these disciplines lay many new discoveries for science."